Standard & Poor’s Ratings Services on Friday cut its credit rating on Saudi Arabia, saying the tumble in oil prices is driving a wider government deficit. S&P lowered its rating by one notch to A-plus from double-A-minus. The rating is now four notches below the premier triple-A rating. S&P maintained its negative outlook on the kingdom, saying it could lower its rating in the next two years if the government doesn’t reduce the deficit. The ratings firm said it expects Saudi Arabia’s deficit to increase to 16% of gross domestic product this year from 1.5% in 2014, largely due to the sharp decline in oil prices. Saudi Arabia is one of the world’s top crude oil-exporters, leaving it heavily exposed to the swings in oil prices.