CREATE TABLE table_17667 ("Year" FLOAT, "Division" FLOAT, "League" TEXT, "Regular Season" TEXT, "Playoffs" TEXT, "Open Cup" TEXT)

What is the lowest year that regular season is 4th, Rocky Mountain?
SELECT MIN("Year") FROM table_17667 WHERE "Regular Season" = '4th, Rocky Mountain'
SELECT MIN("Year") FROM "table_17667" WHERE "Regular Season" = '4th, Rocky Mountain'