Between months from April to July, Windows Phone installed base has grown by 0.3%, which means hitting its highest percentage of subscribers at 3.6% in last two-year. This means 6.23 million Windows Phone users in US market in the month of July 2014.
Windows Phone user base was at 3.4% in month if June and this will mean addition of around 350,000 new users in last month. This perhaps may be due to strong performance of Lumia 630 as underlined by Adduplex data. Lumia 630 already accounts for 5.2% of sales share of windows phone in US.