San Jose, Calif. -- Nearly half (40%) of retailers will add a mobile version of their website in 2013, with 20% planning to create a mobile app, according to the "2012 ECommerce Trends Survey,” a survey of nearly 500 global retailers conducted by SLI Systems. Retailers’ biggest challenges in e-commerce continue to be improving conversions (63%) and attracting more customers to their websites (61%), the survey revealed.