Northern Living Allowance - Taxable travel benefit on Box 32  of your T4 slip

Is the taxable travel benefit amount received from your employment in the prescribed zone shown in Box 32 of your T4 slip for the year or per trip. ex. Box 32= $1,000 , 2 non-medical trips per year is this $1,000/trip or $500 per trip = $1,000/year.