Can you afford to wait another year for oil prices to rise? Can you afford not to buy oil stocks before they do? Oil stocks tumbled on Tuesday, with both ExxonMobil (XOM -2.18%) and ConocoPhillips (COP -2.35%) shares sliding 2.8%, and Shell (SHEL -3.04%) falling 3.2% through 10:10 a.m. ET. After strengthening to a recent high north of $77, West Texas Intermediate (WTI) crude oil prices turned tail and began falling last week. At roughly $70.60 per barrel, crude oil today costs 9% less than it did just a wee ...