Mr. X, a business man had the income in the year $2000$, such that he earned a profit of $20$% n his investment in the business. In the year $2001$, his investment was less by Rs. $5000$ but still had the same income (Income=Investment+Profit) as that in $2000$. Thus, the percent profit earned in $2001$increased by $6$%. What was his investment in $2000$?