You can thank French President Emmanuel Macron, but I'm sure you won't.
Most migrants were leaving from Libya which had been in chaos since we encouraged their Arab Spring in 2011. But good old Macron, as soon as he was elected, brokered a ceasefire between various warring factions in Libya, some of whom were funding their war by trafficking migrants. The Italian navy have been given permission to enter Libyan waters, and smuggling through the western Sahara has also been tackle.
The problem hasn't been completely solved, but it is a good step in the right direction.
https://www.economist.com/blogs/economist-explains/2017/07/economist-explains-27