(a) Tribal shares are determined by using the NTTFI as calculated for fiscal year 2012, and the most recent data on American Indian and Alaska Native population within each Indian Tribe's American Indian/Alaska Native Reservation or Statistical Area, as computed under the Native American Housing Assistance and Self-Determination Act of 1996 (25 U.S.C. 4101 et seq.), in the following manner:

(1) 27 percent in the ratio that the total eligible road mileage in each Tribe bears to the total eligible road mileage of all American Indians and Alaskan Natives. For the purposes of this calculation, eligible road mileage will be computed using only facilities included in the inventory described below:

(i) Were included in the BIA System Inventory prior to October 1, 2004;

(ii) Are owned by an Indian Tribal government;

(iii) Are owned by the Bureau of Indian Affairs.

(2) 39 percent in the ratio that the total population in each Tribe bears to the total population of all American Indians and Alaskan Natives; and

(3) 34 percent will be initially divided equally among each BIA Region.

(b) The share of funds will be distributed to each Indian Tribe within the BIA Region in the ratio that the average total relative need distribution factors and population adjustment factors from fiscal years 2005 through 2011 for a Tribe bears to the average total of relative need distribution factors and population adjustment factors for fiscal years 2005 through 2011 in that region.