I'd say that kids 12 and under were were a constant target audience over the course of the series. It seems that parents were more of a target audience in the early seasons, and became less a target audience as the show progressed. I'd also say that single women were probably a target audience in the early seasons, since Jesse's character was intended to appeal to women, and was initially played up as such. I doubt teenagers were ever a specific target audience, though the more mature and risque adventures that happpend to DJ and Stephanie as they got older would appeal to teenagers. However, if they had wanted to make teenagers the target audience in the later seasons, they likely wouldn't have made Michelle the centre of so many plots.