pre_text: operating expenses as a percentage of total revenue .
post_text: operating expense summary 2006 compared to 2005 overall operating expenses increased $ 122.5 million in 2006 , as compared to 2005 , primarily due to : 2022 an increase of $ 58.4 million in stock-based compensation expense due to our adoption of sfas no . 123r ; and 2022 an increase of $ 49.2 million in salary , benefits and other employee-related costs , primarily due to an increased number of employees and increases in bonus and commission costs , in part due to our acquisition of verisity ltd. , or verisity , in the second quarter of 2005 . 2005 compared to 2004 operating expenses increased $ 97.4 million in 2005 , as compared to 2004 , primarily due to : 2022 an increase of $ 63.3 million in employee salary and benefit costs , primarily due to our acquisition of verisity and increased bonus and commission costs ; 2022 an increase of $ 9.9 million in stock-based compensation expense due to grants of restricted stock and the assumption of options in our acquisitions ; 2022 an increase of $ 8.6 million in losses associated with the sale of installment contract receivables ; and 2022 an increase of $ 7.1 million in costs related to the retirement of our executive chairman and former president and chief executive officer in 2005 ; partially offset by 2022 our restructuring activities , as discussed below . marketing and sales 2006 compared to 2005 marketing and sales expenses increased $ 39.4 million in 2006 , as compared to 2005 , primarily due to : 2022 an increase of $ 14.8 million in stock-based compensation expense due to our adoption of sfas no . 123r ; 2022 an increase of $ 18.2 million in employee salary , commissions , benefits and other employee-related costs due to increased hiring of sales and technical personnel , and higher commissions earned resulting from an increase in 2006 sales performance ; and 2022 an increase of $ 7.8 million in marketing programs and customer-focused conferences due to our new marketing initiatives and increased travel to visit our customers . 2005 compared to 2004 marketing and sales expenses increased $ 33.1 million in 2005 , as compared to 2004 , primarily due to : 2022 an increase of $ 29.4 million in employee salary , commission and benefit costs due to increased hiring of sales and technical personnel and higher employee bonuses and commissions ; and 2022 an increase of $ 1.6 million in stock-based compensation expense due to grants of restricted stock and the assumption of options in our acquisitions ; partially offset by 2022 a decrease of $ 1.9 million in marketing program costs. .
table: 2006 2005 2004
table: Marketing and sales 27% 28% 28%
table: Research and development 31% 29% 31%
table: General and administrative 10% 10% 7%
question: Analyse this data from a financial earnings document. what portion of the increase of operating expense in 2006 is incurred by the increase in stock-based compensation expense due to our adoption of sfas no?