The dollar amounts specified in RCW 49.62.020 and 49.62.030 must be adjusted annually for inflation. Annually on September 30th the department of labor and industries must adjust the dollar amounts specified in this section by calculating to the nearest cent using the consumer price index for urban wage earners and clerical workers, CPI-W, or a successor index, for the twelve months prior to each September 1st as calculated by the United States department of labor. The adjusted dollar amount calculated under this section takes effect on the following January 1st.