Here are numbers for world wide market share of units shipping for smartphones and tablets:
In smartphones Apple has 13.1% of the smartphone market in 2Q13, down from 16.6% last year.
In tablets Apple has a 35.5% share, while the TrendForce change from last year is not listed, IDC shows 68.2% for Apple market share in 2Q12 (IDC totals may not include "White Box" tablets, so think more like 50% to be safe). Regardless, this drop is simply astounding. Without major changes, Apple could be relegated to niche status 2 years from now.
I've not seen breakout numbers for Windows Tablets yet, though judging from the Microsoft numbers listed, I think it likely they do not top 5%. [Generally, the rest would be Android, which is likely around 60%.]
Fascinating to me, "White Box" tablets are shown at 23.5% of the market. Many of the market share analysts were not counting them last year, which I thought was shameful as they really were making up a significant piece of the market then (probably less than the 23.5%). These tablets tend to be much cheaper and have lesser hardware, especially w.r.t. display resolution. They have shown marked quality improvements in the last year or so. The hard part of course is picking out the bad ones from the good ones, though you'll find many in Amazon's Best Selling Tablets list.
Here's some articles covering the matter:
Apple Inc. (AAPL) Is No More World's Most Profitable Phone Maker
Apple Inc's smartphone market share slips to lowest since 2009
iPad market share is the lowest its ever been; Android catching up
iPad Market Share Q2 2013: Apple tablet share falls to all-time low