I'm a bit behind on June's report, but here's another revealing peek at Windows Phone device usage statistics, courtesy of AdDuplex. This month, we see how well the Lumia 630 is growing and take a look at a separate but related report about how well Windows Phone usage is doing on a country-by-country basis. The surprise? USA has more Windows Phone handsets than anywhere else.

So there are two things going on here. First is the AdDuplex June report about Windows Phone usage. Not sure what happened when this arrive in my inbox a few weeks ago, but I'm catching up now, sorry. The second is a look at a rough look at Windows Phone usage by country.

As you may remember, AdDuplex bills itself as the largest cross-promotion network for Windows Phone and Windows 8 apps, empowering developers and publishers to promote their apps for free by helping each other. And each month it provides a tantalizing glimpse at which Windows Phone (and Windows) devices people are actually using.

Here's what's happening.

In its June report about Windows Phone usage, AdDuplex noted the following:

Top three the same, but some trends are developing. The top three most-used Windows Phone handsets in the world are still the Lumia 520, Lumia 625 and Lumia 920, respectively, but each is now on the way down.

Lumia 630 jumps to number 20. In May, the then-new Lumia 630 was in 30th place, usage-wise, but this month it has jumped to number 20. Since this device (and its sister Lumia 635) are basically the replacement for the Lumia 520, this will be one to watch.

Windows Phone 8.1 usage continues to grow. With Windows Phone 8.1 out in the world via the developer preview program and a handful of new phones, usage is starting to grow: In June, 7.7 percent of all Windows Phones in use were on 8.1, up from 5.2 percent in May. With Windows Phone 7.x at 17 percent and falling, I'm thinking Windows Phone 8.1 overtakes that older system very quickly, especially since wireless carriers are due to start opening up the upgrade gates any day now.

Nokia holds steady as competition really ramps up. With more and more Windows Phone hardware makers coming on board with new devices each month this year, I'm curious to see when or if Nokia usage share starts to fall. But it remained at almost 94 percent of all Windows Phones in use in June. But this month, Micromax, Panasonic and Prestigio finally show up in the usage stats, and AdDuplex notes a ton of new phones there are showing up in its logs including devices from Longcheer, JSR, AllView, Honeywell, Micromax, Panasonic, K-Touch, Prestigio, Blu, InFocus, and Lenovo. (Lenovo!)

New Nokia devices on the way. And speaking of new devices, there are some new Nokia devices coming, including an 8.1-based handset with a 5-inch 720p screen. Model numbers are RM-983, 984 and 985.

Lumia 520 and 521 account for over half of all Windows Phones in use in the USA. Growth in both has stopped, but the Lumia 520 (18 percent) and Lumia 521 (33.8 percent) now account for over half (51.7 percent) of all Windows Phones in use in the United States.

OK, so that is all very interesting. But I'm really curious about this newer chart too. This shows which countries (roughly) have the most Windows Phone handsets in use. And curiously enough, both the USA (#1) and China (#6) are both in the top ten. Which is good, because we keep hearing about how terribly Windows Phone is doing in those markets.

So 11 percent of all Windows Phones in use worldwide are in the US, 7.5 percent are in India, 6.9 percent are in Brazil, 4.3 percent are in Russia, and 4.3 percent are in Italy. (China sits at 3.7 percent.) Interesting stuff.