Table A2-24 First-Class Mail -- Nonpresort Envelopes by Sector (Percentage of Total Envelopes) Postal Fiscal Years 1987, 2006 and 2007 (Diary Data)
Sector	1987	2006	2007
Household-to-household	12.5	12.7	12.2
Household-to-nonhousehold	17.3	30.5	34.0
Nonhousehold-to-household	25.2	30.5	31.3
Unidentified incoming	0.5	2.5	2.1
Unidentified outgoing	2.5	1.9	2.3
Subtotal	58.0	78.1	81.8
Nonhousehold-to-nonhousehold	42.0	21.9	18.2
Total	100.0	100.0	100.0
Base: RPW Total, First-Class Envelopes.
Note: Totals may not sum due to rounding.