The wearable market's global sales volume is expected to surpass 51 million units this year,... nearly three times that of last year.br Germany-based GfK market researcher forecasts the growth to be led by sales of smartwatches... that are expected to expand by six-and-a-half times this year compared to a year ago.br The research firm says... the market will expand even further... as major global electronics companies... like Apple and LG Electronics... jump into the race.