Android-based tablets further solidified their status in the global market with their market share nearing 70 percent, data showed on Tuesday.   According to the data compiled by Strategy Analytics, some 34.6 million Android tablets were shipped in the second quarter of the year, up from 18.5 million shipped a year earlier. Their market share stood at 67 percent, also up from 51.4 percent over the cited period.  Apple Inc. shipped 14.6 million units in the April-June period, down from 17 million a year earlier, and its market share also took a nosedive, falling from 47.2 percent to 28.3 percent over the cited period, the data showed. It is the first time Apple\'s market share has hovered below the 30-percent mark. Its market share stood at 79.2 percent in 2010, 52.7 percent in 2011 and 38.4 percent in 2012. Global tablet shipments reached 51.7 million units in the second quarter. Microsoft captured a niche 4.5 percent global tablet share in the second quarter by moving 2.3 million units, according to the data.