this section. (4) Monthly grant payment amounts (A) In general Subject to paragraph (5), the Secretary shall pay to each State that is awarded a grant under this section, for each month during the State's grant period (as defined in subparagraph (C)), an amount equal to 15 percent of the amount determined for the State under subparagraph (B). (B) Average monthly HCBS expenditures The amount determined for a State under this subparagraph is the amount equal to— (i) the sum of— (I) the average annual amount of State expenditures under title XIX of the Social Security Act ( 42 U.S.C. 1396 et seq.) that are attributable to providing medical assistance for home and community-based services for the 3 most recent fiscal years for which data is available