As at 31 December 2010, the remuneration of ministers depended on which ministerial grade – from the lowest to the highest, MR4, MR3, MR2 or MR1 – they were at. Each minister's pay package was made up of fixed components (a monthly salary for 12 months, a non-pensionable annual allowance of one month's salary, a special allowance of one month's salary, and a public service leadership allowance of two months' salary) and variable components (an annual variable component, a performance bonus, and a gross domestic product (GDP) bonus). The annual variable component of up to one and a half-month's salary was paid based on Singapore's economic performance. In years where economic performance was exceptional, a special variable payment was also made. Each minister's performance bonus was determined by the Prime Minister and could be up to 14 months' salary, though most good performers received the equivalent of nine months' salary. The GDP bonus depended on the nation's GDP growth rate. No bonus was paid if the rate was below 2%, and a maximum bonus of eight months' salary was paid if the rate was 10% or greater. In addition, ministers received the same medical benefits as civil servants. In 2010, the benchmark annual remuneration for an MR4-grade minister was $2,598,004, while the actual salary paid was $1,583,900. An MR1-grade minister's salary was $2,368,500. The annual pay of the Prime Minister was set at a fixed ratio to the MR4 salary, and was $3,072,200 in 2010. This included a fixed service bonus in lieu of a performance bonus since there was no one to assess the Prime Minister's individual performance. The fixed service bonus was the same as the performance bonus paid to a good performer at the MR4 grade.