The sum of one hundred thousand dollars ($100,000) is hereby appropriated to the Department of Labor and Industry for the Subsequent Injury Fund by the Commonwealth for the 1971-1972 fiscal year and this fund shall be maintained at one hundred thousand dollars ($100,000) by assessing each insurer a proportion of the amount expended from the fund during the preceding year, that the total compensation paid by such insurers during such year bore to the total compensation paid by all insurers that year: Provided, however, That in the first year in which assessments are made under this provision, the total amount assessed and collected shall be two hundred per centum of the amount paid in such cases during the preceding year.