Global Payment Gateway Market Assessment, By Type [Hosted Payment Gateways, Self-Hosted Gateways, API-Based Gateways, Direct Payment Gateways, Local Bank Integration Gateways], By Company Size [Large Enterprises, Small and Medium-Sized Enterprises], By Industry [Banking, Financial Services and Insurance, Retail and E-Commerce, Travel and Hospitality, Media and Entertainment, Healthcare, Others], By Region, Opportunities and Forecast, 2017-2031F