user: Question: What is the lowest year that regular season is 4th, Rocky Mountain?
Columns: ['Year', 'Division', 'League', 'Regular Season', 'Playoffs', 'Open Cup']
Types: ['real', 'real', 'text', 'text', 'text', 'text']
Sample row: [1998.0, 4.0, 'USISL PDSL', '4th, Central', 'Division Finals', '1st Round']
SQL:

assistant: SELECT MIN("Year") FROM "Table" WHERE "Regular Season" = '4th, Rocky Mountain';