Occasionally, it may be necessary to estimate employment at the DOT level for a point in time earlier than what the Job Browser Pro methodology currently supports. Here is a suggested way to roughly estimate further back in time. It requires use of a spreadsheet program and zip file extraction.

Prior to 1997, the only available wage and employment data available was reported by 3-digit Census 1990 number. Contact SkillTRAN to see if this data remains available.
From 1997-2000, OES 1990 codes were in use to categorize the OES (SOC) occupations. It is a 5-digit number.
From 2000-2009, SOC 2000 codes were in use to categorize the SOC occupations. It is a 6-digit number.
In 2010 and after, SOC 2010 codes were in use to categorize the SOC occupations. It is a 6-digit number.

The trick is to consider the industry suggestions today to choose whether today's percentage of the labor market today applies to an earlier time period.

Here is the approach:

Use Job Browser Pro to do the following:
1. Look up the DOT occupation – e.g. 344.667-010 Ticket Taker
2. On the Description page, click Quick View to see the occupation code for the time period needed ... e.g. SOC2000 code: 39-3031 Ushers, Lobby Attendants, and Ticket Takers
3. Close the description page, then open the Employment Numbers Page > DOT Employment Estimate
4. There are 5 DOT occupations in this SOC group. In the lower right corner, determine whether the 22.xxx% figure fits with your understanding of the likely frequency of this occupation for full-time/part-time employment. Consider whether employment may have been influenced over time by automation, outsourcing, or other influences that might affect employment for the year needed.
5. When you have settled on a suitable percentage to use, go to http://www.bls.gov/oes/tables.htm (for 1997 and later) and scroll down to your target year, choosing National, State, or Metropolitan area statistics as needed.
6. Download the chosen spreadsheet file by clicking on it. Extract all the files in the .zip file (usually right click, Extract All) to a location you prefer.
Open the larger file. Scroll down the list to find the row for occ_code = 39-3031, then note the tot_emp value (total employment) in column D.
Example: For May 2002, total employment was 106,050 employed nationally for SOC 39-3031 - Ushers, Lobby Attendants, and Ticket Takers
7. Multiply the tot_emp value times the percentage you chose. So 106,050 x 22% = 23,331 is the estimated number of Ticket Taker.
8. Repeat this process for each of the other occupations.

Recognize that this is a rough estimation process which applies today's staffing pattern to yesterday's data. No estimation is "perfect" unless there is but one DOT in a a given SOC group.