// the pin where the temperature is to be mesured
int lightPin = 5;

void setup()
{
  // open te serial output with 115200 baud  
  Serial.begin(115200);
}

void loop()
{
  // read the light
  int lightReading = analogRead(lightPin);    
  // calculate the percentage
  float percent = lightReading / 1024.0 * 100;  
  // round to two decimals
  percent = floor(percent*100) / 100;
  // print it on the serial output
  Serial.println(percent);
  // wait a second
  delay(1000);
}