Throughput Calculation for Trace FIle

I have an awk file to calculate throughput for my trace file called
output.tr.

>* ===================== throughput.awk ===============================
*> >* BEGIN {
*>*         recv = 0
*>* }
*> >* {
*>*         # Trace line format: normal
*>*         if ($2 != "-t") {
*>*                 event = $1
*>*                 time = $2
*>*                 if (event == "+" || event == "-") node_id = $3
*>*                 if (event == "r" || event == "d") node_id = $4
*>*                 flow_id = $8
*>*                 pkt_id = $12
*>*                 pkt_size = $6
*>*         }
*>*         # Trace line format: new
*>*         if ($2 == "-t") {
*>*                 event = $1
*>*                 time = $3
*>*                 node_id = $5
*>*                 flow_id = $39
*>*                 pkt_id = $41
*>*                 pkt_size = $37
*>*         }
*> >*         # Calculate total received packets' size
*>*         if (flow_id == flow && event == "r" && node_id == dst) {
*>*                 if (flow_t != "sctp") {
*>*                         recv += pkt_size - hdr_size
*>*                         #printf("recv[%g] = %g --> tot:
*>* %g\n",node_id,pkt_size-hdr_size,recv)
*>*                 } else {
*>*                         # Rip off SCTP header, whose size depends
*>*                         # on the number of chunks in each packet
*>*                         if (pkt_size == 40) pkt_size = 0
*>*                         if (pkt_size == 448) pkt_size = 400
*>*                         if (pkt_size == 864) pkt_size = 800
*>*                         if (pkt_size == 1280) pkt_size = 1200
*>*                         recv += pkt_size
*>*                         #printf("recv[%g] = %g --> tot:
*>* %g\n",node_id,pkt_size,recv)
*>*                 }
*>*         }
*>* }
*> >* END {
*>*         printf("%10g %10s %10g\n",flow,flow_t,(recv/simtime)*(8/1000))
*>
* }*

When I run the command awk -f thr.awk output.tr, get an error in the simulation:
awk: thr.awk:31:  %g\n",node_id,pkt_size-hdr_size,recv)
awk: thr.awk:31:  ^ syntax error
awk: thr.awk:31:  %g\n",node_id,pkt_size-hdr_size,recv)
awk: thr.awk:31:    ^ backslash not last character on line

How can i fix this problem?