Currency Pairs:
1.Majors: EUR/USD (Euro-Dollar), USD/JPY, GBP/USD - (commonly referred to as the "Cable"), USD/CHF
2.Dollar bloc: USD/CAD, AUD/USD, NZD/USD - (commonly referred to as the "Kiwi")
3.Major crosses: EUR/JPY, EUR/GBP, EUR/CHF

Average Daily Turnover by Currency Pair

Source Link:

http://www.goforex.net/forex-market-snapshot.htm